Utilization of anhydrous aluminum chloride sludge



May 20, 1958 A PARDEE 2,835,554

UTILIZATION OF ANHYDROUS ALUMINUM CHLORIDE SLUDGE Filed Dec. 23, 1554 3Sheets-Sheet 2 I I INVENTOR. I W/LL/AM 4.1242065 x/g ATTORNQ y ,1958 w.A. PARDEE 2,835,554

UTILIZATION OF ANHYDROUS ALUMINUM CHLORIDE SLUDGE Filed Dec. 25, 1954 ssnets-sheet 3 United States Patent Ofiice 2,835,554 Patented May .20,1958 UTILIZATION OF ANHYDROUS ALUMINUM CHLORIDE SLUDGE William A.Pardee, Fox Chapel, Pa., assignor to Gulf Research 85 DevelopmentCompany, Pittsburgh, Pa., a corporation of Delaware Application December23, 1954, Serial No. 477,247

Claims. (Cl. 23-93) This invention relates to utilization of anhydrousaluminum chloride sludge and more particularly to a process whereinaluminous ore, bauxite, is introduced into a rotary kiln, is heatedtherein to a temperature of approximately 1600 F., is saturated withmolten aluminum chloride sludge during its passage through the saidkiln, the said molten aluminum chloride sludge being applied to thebauxite at a multiplicity of spaced points, and the said sludge iscarbonized in the pores of the bauxite during the heating, thus formingan intimately combined and highly reactive aggregate of bauxite,alumina, and carbon; and wherein the said highly reactive aggregate isintroduced into a retort at the necessary reaction temperature and isthere reacted with chlorine to produce anhydrous aluminum chloride; andwherein the anhydrous aluminum chloride is finally condensed andseparately obtained.

Anhydrous aluminum chloride is used as a treating agent in themanufacture of hydrocarbon lubricating oils, and also as a catalyst inthe isomerization and in the alkylation of light hydrocarbons. In theconduct of these operations the anhydrous aluminum chloride is degradedand it ends up as a heavy black sludge, asphaltic in appearance. Thesesludges are ordinarily either solid or highly viscous at atmospherictemperatures and they contain some aluminum chloride, heavy polymerichydrocarbon products, and other products of reaction of aluminumchloride with hydrocarbons. Many attempts have been made to utilizethese aluminum chloride sludges, and particularly to recover theircontent of anhydrous aluminum chloride, but no recovery process hasheretofore been commercially successful. As a consequence, the disposalof large quantities of this sludge has become a very serious problem tousers of aluminum chloride. This disposal problem in some plantsinvolves several thousand barrels of such sludge each day. While I havenot at this time succeeded in devising a method of recovering theanhydrous aluminum chloride content of the sludge, I have devised amethod of recovering the aluminum content of the sludge and also itscarbon content.

The sludge, when separated from the hydrocarbons with which it has beenused, and after cooling to atmospheric temperature, becomes a solidblack mass of low ducility. One satisfactory method of handling thesludge is to hydrolyze it with a substantial amount of water, and inthat condition it can be pumped as a slurry. The aluminum chloridesludge which I use in the preparation of an aggregate with aluminousmaterial is first hydrolyzed, and the following table gives propertiesof two characteristic sludges of this character.

The hydrolyzed sludge softens at temperatures little above F. and it isquite fluid at a temperature of about 200 F. When this material israised to the temperatures which I use in the preparation of myaggregate, I am able to recover the asphaltic content of the sludge ascarbon and I am able to recover the aluminum content of the sludge asalumina, A1 0 The carbon that I recover from this sludge is ordinarilyabout one-fifth the'weight ot' the hydrolyzed sludge, dry, and the A1 0recovered is ordinarily about one-tenth the weight of the dry sludge.

In my present invention I prepare an aggregate of bauxite and aluminaand carbon in which the bauxite and alumina are thoroughly impregnatedwith the carbon, the carbon being in such intimate and uniform contactwith the bauxite and alumina that the reaction between these solids andchlorine gas is greatly facilitated and can be effected at temperatureswithin the range of approxi-" mately 1000 F. to 1500 R, which range ismuch below that which has previously been possible. This impregna tionof bauxite and alumina with carbon is effected by introducing thebauxite in relatively finely divided form into a heated rotary kiln inwhich it is heated and at least partially saturated with molten aluminumchloride sludge, by continuing the heating of the bauxite and aluminumchloride sludge mixture (herein sometimes referred to asmaterial-in-process) to a point at which the sludge is at leastpartially carbonized by adding further molten sludge to thematerial-in-process at a number of successive points during its progressthrough the rotary kiln and so spacing the points of sludge introductionas to per-' mit at least partial carbonization of each charge of sludgeprior to the introduction of the next such charge and completecarbonization before discharge of the aggregate from the kiln.

The aggregate prepared in the manner just described from the rotary kilnat a temperature of approximately 1600 F. or sufliciently thereabove topermit its introduction at approximately that temperature, or somewhatlower, into a chlorinating retort for reaction with chlorine andcreation thereby of anhydrous aluminum chloride. The aluminum chloridevapors are then condensed and separately obtained.

One primary purpose of this invention is to prepare an lntermediateproduct in the form of an ore-carbon aggregate in which the twoaluminous materials bauxite and alumina are in unusually intimatecontact with the carbon and in which the carbon itself is in uncommonlyreactive condition, the aggregate being of unprecedentedly high poresurface area and susceptible of chlorination at temperatures of theorder of 1000 to 1500" F. These temperatures compare with temperaturesof 1650 to more than 2000 in the prior art. The lower temperature ofchlorination possible with my aggregate prevents the conversion of thebauxite and alumina to the less reactive forms into which thesealuminous materials are transformed at higher temperatures, keeps itmuch more porous in the chlorination retort, and greatly speeds up therate of reaction, all this with a substantial diminution of thenecessary retort capacity and a substantial decrease in the productionof unreactive bauxite.

In the preparation of my aggregate the aluminous material is thoroughlysaturated with molten aluminum chloride sludge and the sludge is thencarbonized in the pores of the aluminous material. It is particularlyeffective, convenient and economic to perform this process in aninclined rotary kiln of the character commonly referred to as ahorizontal rotary kiln, wherein the ma terial-in-process can be tumbledand mixed and directly heated simultaneously.

in the pores of the bauxite. and alumina in proportions of from 0.45 tomore than 1.0 pound of carbon per I find that an aggregate containingsuch a percentage of 1 carbon is best prepared by adding and carbonizingthe aluminum chloride sludge 1118. series of increments, each incrementproportioned to add approximately three percent to seven percent or moreof carbon to the aluminous nr'aterial These increments areadvantageously proportioned with the lower percentages at the cooler endof the horizontal rotary kiln and the higher percentages at thehotter-end of the kiln. Also the spacing of the points at whichsuccessive increments are introduced is advantageously somewhat greaterat the cooler end of the kiln than at the hotter end of; the kilnbecause the partially cooled gases require more time, and therefore moreen th, to ac omp h t oar onizat on than d the hotter gases at thefurnace end of the, kiln.

Referring to, the accompanying drawings:

F ur L is a. r ss; sec i n w of. he o a y kiln and. its. re ate p rts-Eis r i n levati n. ew f the lorination pparatus.-

Figure 2, is a cross section view taken on. AA, of Figure 1...

Figure 3 is a cross section view of the rotary kiln, showing a,convenient style of longitudinal bars of lifters the e n,v

Figure 4, is a cross section view of element 31, and related parts,takenon B B of Figure 1.

Referring to Figure 1, numeral 1 indicates a horizontal rotary kiln,extending from furnace chamber 2 at its lower endfto stack 3 at itsupper end. A raw material bin for material to. be processed is indicatedby numeral 4 and a ch t 5 extends from the base of bin 4 into the upper(charging); end of kiln 1. Flow of material from bin 4 to kiln 1 iscontrolled by gate 28. The kiln is heated. by burner 6, this burnerbeing set back in furnace chamber 2 so that its flame will not ignitethe molten sludge introduced, as hereinafter described, at the nearestnozzle 39. Thekiln 1. discharges processed material at its lower and no. ecei ing in 9; which p rated from. furnace.

chamber 2 by wall. 10., A chute 11 extends from the base of receivingbin 9 to the base of elevator 12, and agate 2 9 is provided to controlthe flow of material from bin 9 to elevator 12.

Aja keted conduit 31; extends through the entire length oflhorizental.rotary kiln 1, with its respective ends extending through, and outbeyond stack 3 and furnace.

chamber 2. I,t may be supported by the walls of these members 3 and 2orby separate supports. Conduit 31 is-fitted with a series of spraynozzles 39 and it carries inits;interiqr a number of separate smallerconduits, 34 to 37jinclusive (subsequently described in connection withFigure 4) which extend from the individual spray nozzles to headers 41'and 42. Conduit 31 is also fitted with flanges 43 and 44 adjacent itsrespective ends to permit the introduction and circulation of steam orsome other temperature controlling fluid in conduit 31 around, theexterior of the aforementioned smaller conduits.

Referring to Figure 1a, an elevator 12 discharges theprocessed'rnaterial, which at this stage is otherwise referredto asaggregate, into a chute 13 which in turn delivers the material to a bin14; This bin 14 discharges through star-valve 15 into the top ofchlorinating retort. 16. Conduit 1-7 conducts vapors of aluminumclllQridefrom retort 16 to precooler 18. Conduit 19 conducts,precooledvapors from precooler 18 to condensing tubes; 29; and 21,. which are inmutual communication throughbinZfi. Thesetubes 20 and 21 areadvantageously surrounded by. water jackets which, for simplicity ofrepresentation, are not shown. Each of condensing tubes 20 and 21 has ashaft 22 in axial alignment therewith and each of these shafts 22carries a series of scraper plates- 23 positioned to sweep the condenserwallsfrom top. to. bott mJand fastened to the shaft 22 by means- 4 of anumber of short lengths of chain. Each shaft 22 also carries a pulleywheel 24 at its head, through which it may be rotated. This rotation ofshafts 22 throws the scraper plates 23 out against the interior walls oftubes 20 and 21, to dislodge aluminum chloride condensed thereon. Bin 26collects condensed aluminum chloride scraped from the interior walls oftubes 20 and 21 and this alumi num chloride is emptied from bin 26 byremoval of plate 27. A horizontal Archimcdean screw can be convenientlysubstituted for plate 27. A tail-pipe 25 is provided to conductuncondensed gases from the equipment.

Referring to Figure 2,. this is a cross section taken on section line AAof Figure I. Figure 2' shows the dischargeend of chute 5 and it showsjacketed conduit 31. Conduit 31 is positioned with its longitudinal axisparallel to the longitudinal axis of horizontal rotary kiln 1, and itsaxis will, he at, a point high enough to spray liquid asphalt onto thecontents of the kiln from nozzle 39. Thelongitudinal axis of jacketedline 31 may be positioned, somewhat to the side, of the vertical axisof, the kiln 1. in order to avoid having the material-inprocess fallupon it during rotation of the kiln. Numeral 30 identifies a, dotted;line depicting the approximate, sur' face of the discrete material-inprocess while the kiln is rotating in a contra-clockwise direction.

Figure 3 is a cross sectional, view of kiln 1 showing the interiorthereof fitted with a series of longitudinal ledges or lifters 40 toincrease the agitation of discrete material-in-process during; itsprogress through the kiln. These have some advantages in the hotter endof the kiln.

Figure 4 is a cross section of jacketed conduit 31,. taken on sectionline B-B of Figure 1. In this view, numeral 31 indicates the metallicconduit and 32 indicates a heavy jacket of insulating material whichentirely surrounds conduit 31. Numerals 33, 34, 35, 36, and 37' indicatea; series of smaller separate conduits inside of conduit 31 which, leadto individual spray nozzles 39 and which, terminate at their other endat header 41 or 42, at which, point they are connected to individualsupply. lines, nots-hown. The number of these smaller conduits; is;determined by the needs of the process: as hereinafter: discussed. Eachof the conduitsof the series 33 to 37 inclusive. is connected to a spraynozzle 39 through a; connection 38-. Figure 4. shows themanner oftheconnectionzfrom. smaller conduit 36 to its nozzle 39.

Figure; 5. is: a modification of the kiln shown in Figure 1;. All. thenumbered. parts of Figure 5 correspond to-those of Figure l, and. thedifference between the ap- Paratus of'Figure l and that. of Figure 5' isthat the furnace 2 and the stack 3 in Figure 5: are at ends of the kiln1 oppositeto those shown. in Figure 1. In the apparatus: of Figure. lthe material-improcess and the combustion. gases: flow. in. the samedirection.

In the practice of this invention bin 4 is loaded with bauxite ore ofapproximately half inch and" less in size. There is advantage in having.the bauxite fairly fine. Kiln 1, rotated by means of gears 8, is put inoperation. Burner 6 is ignited to provide thenecessary heat for theoperation. Ore from bin 4 is passed through chute 5 intohorizontalrotary-kiln 1. A gate 28 or star-valve or other. device of similarfunction is positioned to control the flow of bauxite from bin 4 intokiln 1.

When the operation is well established and conditions have attained?equilibrium the material being processed will discharge over fiange- 7'of kiln. 1' into bin 9 at a temperature of approximately 1600' F. Thebauxite entering the kiln- 1 from bin 4' may be calcined or uncalcincd.bauxite at atmospheric temperature or it may be either of these at asomewhat elevated temperature. Uncalcined bauxite produces: asomewhatmorereactive aggregate.

Molten anhydrous aluminum chloride sludge to be sprayed on the bauxiteduring its passage through the kiln is charged through conduits 33', 34,35, 36and' 37,

'5 all encased in conduit 31. This conduit 31 is exposed to the hightemperature gases in kiln 1 and to prevent overheating and possiblecoking of the sludge in conduits 33 to 37 inclusive two separate meansof protection are provided. The first is heavy fireproof insulation 32of minimum heat conductivity. The second is a continuous flow of steamor other temperature controlling fiuid through the conduit 31.v Flanges43 and 44 are provided to receive and discharge the temperaturecontrolling fluid. This temperature controlling fluid may be introducedat either end or it may with some advantage be conducted in a closedpipe inside conduit 31 to a point part way through the length of conduit31 and discharged therefrom to both ends 43 and 44.

It is desirable to be able to positively control the amount of moltensludge introduced at each point of introduction, wherefore a separatepipe of the group 33 to 37 inclusive is provided for each spray nozzle39. The separate pipes connect to either header 41 or header 4-2 and arethere connected to lines from sludge pumps. A separate line from aseparate pump to each individual nozzle 39 permits volumetric control ofthe molten sludge introduced at each nozzle 39 and also serves to reducepossibility of coking a portion of a line or coking a nozzle 39 as wouldoccur much more readily if several nozzles were served by a single lineand the molten sludge were free to flow out through the channel of leastresistance. To minimize the heating of sludge in conduits 33 to 37inclusive by the hot gases in the kiln it is advantageous to extend someof these lines inward from header 41 and some from header 42 accordingto the relative proximity to those headers of the individual terminalnozzle 39 and the severity of the heat in the section of the kiln thatthe conduit must pass through.

While the accompanying drawings show five conduits, 33 to 37 inclusive,for charging molten sludge, it is not necessary that there be thatspecific number. The actual number in any particular installation may begreater or in some special cases somewhat less, according to the kilntemperature and carbonizing characteristics of the sludge. The actualnumber of points of introduction of sludge along the length of the kilnshould be sufficient to permit the individual increments of moltensludge to be so limited in quantity that each individual increment willbe promptly absorbed into the material-in-process and rapidlycarbonized. The aluminum chloride sludge shows no tendency to adhere tothe walls or" the kiln.

The minimum amount of carbon required in an aggregate is that amountwhich will react with all of the combined oxygen of the ore to reducethe same. I have found that the required minimum of carbon to reduce theore is an amount within the range of from 45 pounds of carbon up to 60pounds of carbon per hundred pounds of oxygen in the dry bauxite andalumina. In the preparation of the aggregate it may be necessary to usemore asphalt than that necessary to produce the above amount of carbon,this additional amount going to provide for three other sources ofcarbon consumption, viz: burnohf of carbon in the kiln if excess air ispresent; burnoff of carbon in handling the hot briquettes from kiln tosubsequent processing apparatus; and burn-ofi in the final processing(e. g. chlorination) if air or oxygen is introduced at that stage tomaintain the temperature of reaction or for other purposes. Themagnitude of these three demands for carbon is determined exclusively byconditions of operation, which are within the control of the operator,and this additional carbon should be provided according to need.

In a kiln which operates with the furnace gases flowing countercurrentto the material-in-process, and with the gases leaving the kiln andentering the stack 3 at from 600 to 800 F., the maximum percentage ofmolten sludge that can ordinarily be introduced at the stack end of thekiln is such as will add about three percent to five percent of carbonto the aluminous material, measured after the molten sludge iscarbonized by the heat in the kiln. With a temperature of 1700" to 2000F. for the furnace gases entering the kiln at the hot end, the maximumpercentage of molten sludge that can ordinarily be introduced from onenozzle close to that end is such as will add anywhere from about fivepercent to seven and one-half percent of carbon to the aluminousmaterial. Quantities of sludge intermediate the foregoing figures areintroduced at the intermediate nozzles. The introduction of moltensludge at the various nozzles in lesser quantities than those juststated is unobjectionable except that such practice may require agreater number of nozzles and even additional length of kiln.

The minimum amount of molten sludge that must be introduced to produce acertain amount of carbon on the aluminous material is susceptible ofready calculation from the fixed carbon content of the particularasphalt used, but that figure must be increased to allow for the carbonburned as a consequence of any excess air in the combustion gases. Theamount of excess air is solely within the control of the operator, andthis excess air should be kept to a minimum or be totally eliminated,even at the expense of some loss of efficiency in combustion of fuel.

In Figure 2 I have shown the conduit 31 with the nozzle 39 pointingdirectly downward. In some cases it may be more advantageous to rotatethe conduit 31 counter-clockwise about 45, the actual position beingchosen to put the spray of molten sludge on the bauxite and to keep itaway from the shell of kiln 1.

The combustion gases from the burner 6, together with distilled-01fvolatile matter, pass out of the upper end of the kiln into stack 3 anddischarge to the atmosphere.

The material prepared in kiln 1 is finally discharged over flange 7 atthe lower end of the kiln into receiving bin 9, this bin being separatedfrom furnace chamber 2 by means of wall 10. At this stage this materialis aptly termed aggregate. From bin 9 the aggregate flows down chute 11to the base of elevator 12. Passage of aggregate from bin 9 to chute 11is controlled by gate 29 and enough material is maintained in bin 9 tokeep the passage into chute 11 sealed and thereby prevent any tendencyfor furnace gases from furnace 2 to flow thereinto.

If the aggregate discharges from kiln 1 in larger size pieces than aredesired for charging to the chlorination retort, a crusher can beinstalled in the system at a point between bin 9 and the base ofelevator 12. It is not ordinarily desirable to charge to thechlorinating retortany large proportion of pieces of aggregate with amaximum dimension in excess of five inches.

The hot aggregate, after having been crushed if necessary, is elevatedby elevator 12 or a skip-hoist or other equivalent means, dischargedthrough chute 13 (Figure 1a) into charging bin 14, and finally chargedthrough star valve 15 or an equivalent mechanism into chlorinatingretort 16. A sufficient amount of solid material isalways retained inbin 14 to prevent the passage thereinto of chlorine or aluminum chloridevapors from the ehlcrinating retort. The temperature of the aggregateentering chlorinating retort 16 should be between 1200" and 1600 F.,advantageously not in excess of 1500" F.

Entering the bottom of chlorinating retort 16 is conduit 47 carryingchlorine gas from valved conduit 45 and 7 pore surface area commonlyruns one hundred and forty square meters per gram of aggregate andhigher.

The generated vapors of anhydrous aluminium chloride pass from the upperpart of chlorination retort 16 through passageway 17 into a precoolingchamber 18 in which they are advantageously cooled to a temperature ofabout 500 F. or slightly below. The precooler is advantageously anuninsulated metallic chamber with no other cooling medium than thesurrounding atmosphere.

Anhydrous aluminum chloride does not have a liquid phase but sublimesslightly below 370 The vapors leave the precooler at a temperature abovetheir su-bliming temperature and enter vertical condenser column 20.Vapors not condensed in column 20 pass through the upper portion ofcollecting bin 26 into condenser column 21, and tail gases leave thesystem through tail pipe 25.

Condensing columns 20 and 21 are advantageously surrounded by waterjackets in order to minimize their size and to assure substantiallytotal condensation of the anhydrous aluminum chloride. These waterjackets have been omitted from Figure 1a of the accompanying drawings inorder to simplify the representation.

Introduction of oxygen into the chlorinating retort through line 45 willnot ordinarily be necessary once the reaction has gotten established inthe retort, but it can be quite advantageous if the retort temperaturetends to drop below the necessary minimum. Such use of oxygen of courseconsumes a part of the carbon in the aggregate and this use of oxygenshould be accompanied by an increased percentage of carbon in theaggregate being produced in kiln 1 in order that sufficient carbon maybe present in the chlorinating retort to permit ready reduction of thealuminous ore. Any oxygen introduced into the retort may be in the formof air or in the form of oxygenenriched air. In the conduct of myprocess I find air fully adequate without oxygen enrichment.

The foregoing description of my process covers an operation in whichonly bauxite and alumina and molten sludge are charged to kiln 1.However, my process is not so limited and I may charge some coke withthe bauxite, thus reducing the amount of sludge required. When coke ischarged with the bauxite it is broken down to the same size as thebauxite or it may be even smaller in size. In any case, whether or notcoke is charged with the bauxite, the amount of molten sludge used inpreparing an aggregate must be sufiicient to provide the carbonaceousmaterial to saturate the bauxite and to produce an aggregate in whichthe carbon isbound to the bauxite and alumina and is well distributedthrough the pores thereof, forming a uniformly black material. Theaggregate made with bauxite and aluminum chloride sludge alone isuncommonly reactive, having a high pore surface area. It is preferablethat added coke, if any, be a minor proportion in relation to thatformed from the asphalt aluminum chloride sludge in kiln 1. Added cokeis not the equivalent, in my process, of carbon resulting from thealuminum chloride sludge, and the pore surface area of an aggregate inwhich coke has been used will be lower than the pore surface area of anaggregate prepared solely from bauxite and aluminum chloride sludge.

It has been stated that the aggregate produced in kiln I andsubsequently subjected to further processing is charactcrized by anuncommonly high degree of porosity and pore surface area, and that thisgreater porosity appears to be the reason that I am able to attainresults in the chlorination of bauxite that have not previously beenattained. Specific pore surface areas have been given. These poresurface areas have been determined by the well known B. E. T. method,developedby Brunauer, Emmett. and Teller and first published in theJournal of the American Chemical Society, volume 60, at page 309 (1938).This method was subsequently published in A Treatise on PhysicalChemistry, edited by Hugh S. Taylor .and Samuel Glasstone and publishedin 1951 by D. Van Nostrand Company, New York see volume 11, pages 602 etseq.

The pore surface areas given in this application for patent weredetermined with use of nitrogen gas.

By way of specific data on the unprecedentedly high pore surface area ofthe aggregate prepared in kiln 1 by my process I submit the followingscientific determinations:

Bauxite of the analysis given in my first specific example, whencalcined at a maximum temperature of 1600 F. had a pore surface area of121 square meters per gram.

Ordinary petroleum coke, commonly used with bauxite in the preparationof charge for chlorinating retorts, has a pore surface area of less than20 square meters per gram, and often less than 10 square meters pergram.

Aggregate prepared by the process described and claimed herein, andcarbonized at 1600" F. had a pore surface area of square meters pergram.

Some of the aggregate just described above as having a pore surface areaof 140 square meters per gram was ignited at 1000 F., and the bauxiteresidue had a pore surface area of 104 square meters per gram.

The description of my process, up to this point, is directed to anoperation in which the flow of the materialin-process and of thecombustion gases is countercurrent. However, the process can, with equaleffectiveness and advantage, be operated with the material-in-processand the combustion gases flowing in the same direction. The necessaryapparatus for this type of operation is shown in Figure 5, which hasalready been described. When, as in Figure 5, the furnace is positionedat the higher end of the kiln and the material-in-process and thecombustion gases flow in the same direction, it is possible to get thebauxite to a substantially elevated temperature in very short travel andto then apply the molten aluminum chloride sludge to the bauxite at atemperature conducive to prompt saturation and coking.

In contrast with the high temperatures of 1600 to 1800 F. required forchlorination of bauxite and coke mixtures in the past, aggregates madeaccording to the invention herein described will chlorinate about 40%more rapidly at a temperature of 1000 F. than a mechanical mixture offinely divided bauxite and coke will chlorinate at a temperature of 1550F. Operating at 1000" F. my aggregate was repeatedly chlorinated withfrom 93% to 99% conversion of the bauxite. In contrast with theseresults, while conducting the operation in the same manner, I was unableto attain a conversion of more than 56% of the bauxite when operating ata temperature of 1550 F. with a mechanical mixture of finely dividedbauxite and coke, and I was unable to attain a conversion of more than68% of the bauxite in the same mixture when chlorinating at 1800 F.Tests show that my aggregate chlorinates as well at temperatures in therange of 1300 to 1400 F. as was possible at 1800" F. when chlorinatingby previously known methods.

The advantages of my process become apparent in aggregates containing aslow as three to four percent carbon resulting from the sprayed aluminumchloride sludge, The advantages increase with increase of carbonizedsludge and reach a maximum in the case of aggregate containing twenty totwenty-five percent of carbon resulting from the sprayed aluminumchloride sludge. Greater amounts of such carbon do not result in anysubstantial additional advantage.

The relatively low temperatures used in my process are not merelytemperatures which can be used but they are temperatures which should beused. By way of illustrating this point separate but identi al samplesof a bauxite-asphalt aggregate was maintained for a period of sixteenhours in an atmosphere of nitrogen at temperatures of 1550 F., 1800" F.,2100 F., and 2400 F. X- ray diffraction patterns these samples indicatedthe presence of only alpha A1 0 in the samples which had been maintainedat 2100 F. and at 2400 F. The sample maintained at 1800 F. comprisedalpha A1 0 and some transition form of A1 between the gamma and alphaforms. The sample of A1 0 heated at 1550 F. was

Percent by weight A1203 90.8 rio 1.7 sio 4.5 Fe O 1.0

The alchlor sludge had the following properties: Softening point, ringand ball method F. below-.. 74

Volatiles percent.. 69.10 Ash (aluminum oxide) do 9.85 Fixed carbon do21.05

The aggregate was prepared in a horizontal rotary kiln having a lengthof 60 feet and a diameter 6 feet. The bauxite was heated therein in thefirst five feet of travel and at five feet from the entrance it receivedits first spray of liquefied aluminum chloride sludge. Four additionalsprays of liquefied aluminum chloride sludge were charged to thematerial-in-process, these sprays being positioned at distances of 20feet, 33 feet, 44 feet, and 53 feet from the point at which the bauxitewas introduced, the last of these points being seven feet from thedischarge end of the kiln. The liquefied aluminum chloride sludgecompletely penetrated the bauxite and with the furnace chambertemperature at 1900 F. and with gases leaving the kiln at a temperatureof 700, each increment of liquefied aluminum chloride sludge was wellcarbonized before the addition of the next increment. Residence time ofthe material in the kiln was approximately 75 minutes. The fullycarbonized aggregate contained 67 pounds of carbon per hundred pounds ofoxygen in the bauxite and in the aluminum oxide content of the sludge,and the burn-off in the kiln was approximately three percent. Thisburn-off of carbon is, of course, in addition to the distilled-0Evolatile matter.

The fully carbonized aggregate left the kiln at a temperature of 1640 F.and had a temperature of approximately 1400 F. when it entered thechlorination retort. Dry chlorine gas at atmospheric temperature wascharged to the retort through line 35 and the chlorination reactionproceeded smoothly and with the production of no vitreous alumina in thebase of the retort. The anhydrous aluminum chloride was condensed incondenser tubes 20 and 21 and collected in bin 26.

In this specification and the appended claims the term horizontal rotarykiln is used to designate the type of kiln commonly known by thatdesignation, notwithstanding that such kilns are in fact inclined kilnshaving the charging end elevated somewhat above the discharge end.

In the appended claims, when I use the term aluminum chloride sludge, 1means thereby a sludge which has re sulted from the reaction ofanhydrous aluminum chloride with hydrocarbons and which may or may nothave been subsequently hydrolyzed.

I claim:

1. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging aluminous ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the said ore and causing it totravel longitudinally through the said kiln; applying a small percentageof liquefied aluminum chloride sludge to the aluminous ore at a pointnear the charging end of the said kiln; maintaining the temperature inthe said kiln within a range that will carbonize the applied sludge;carboniz-.

ing the applied small percentage of sludge; successively applying andcarbonizing additional small percentages of aluminum chloride sludgewith the said ore during its longitudinal passage through the said kiln;discharging from the kiln an aggregate of fully carbonized aluminumchloride sludge and aluminous material; charging the said aggregate to aretort at a temperature between 1000 F. and 1500" F. and there reactingthe hot aggregate with chlorine gas, thereby producing vapors ofanhydrous aluminum chloride; cooling and condensing the vapors ofanhydrous aluminum chloride and so separately obtaining the same.

2. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging bauxite ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the bauxite and causing it totravel longitudinally through the said kiln; applying a small percentageof liquefied aluminum chloride sludge to the bauxite at a point near thecharging end of the said kiln; maintaining the temperature in the saidkiln within a range that will carbonize the applied sludge; carbonizingthe applied small percentage of sludge; successively applying andcarbonizing additional small percentages of aluminm chloride sludge withthe said bauxite during its longitudinal passage through the said kilnuntil the carbon content of the aggregate is at least 0.45 pound perpound of oxygen in the aluminous content thereof; discharging from thekiln an aggregate of fully carbonized aluminum chloride sludge andbauxite; charging the said aggregate to a retort at a temperaturebetween 1000 F. and 1500 F. and there reacting the hot aggregate withchlorine gas, therebyproducing vapors of anhydrous aluminum chloride;cooling and condensing the vapors of anhydrous aluminum chloride and soseparately obtaining the same.

3. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging aluminous ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the said ore and causing it totravel longitudinally through the said kiln; applying a small percentageof liquefied aluminum chloride sludge to the said ore at. a point nearthe charging end of the said kiln; maintain; ing the temperature in thesaid kiln within a range that will carbonize the applied sludge;carbonizing the applied small percentage of sludge; successivelyapplying and carbonizing additional small percentages of aluminumchloride sludge with the said aluminous ore during its longitudinalpassage through the said kiln; discharging from the kiln an aggregate offully carbonized aluminum chloride sludge and aluminous ore having apore surface area of at least square meters per gram of aggregate;charging the said aggregate to a retort at a temperature between 1000 F.and 1500 F. and there reacting the hot aggregate with chlorine gas,thereby producing vapors of anhydrous aluminum chloride; cooling andcondensing the vapors of anhydrous aluminum chloride and so separatelyobtaining the same.

4. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging aluminous ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the said ore and causing it totravel longitudinally through the said kiln; applying to the said ore ata point near the charging end of the said kiln a small percentage ofliquefied aluminum chloride sludge surficient to saturate the aluminousore therewith; maintain ing the temperature in the said kiln within arange that will carbonize the applied sludge; carbonizing the appliedsmall percentage of sludge; successively applying and carbonizingadditional small percentages of aluminum chloride sludge with the saidaluminous ore during its longitudinal passage through the said kilnuntil the carbon content of the carbonized aggregate is at least 0.45pound per pound of oxygen in the aluminous content thereof;

discharging from the kiln an aggregate of fully carbonized aluminumchloride sludge and aluminous ore; charging the said aggregate to aretort at a temperature between 1000 F. and 1500" F. and there reactingthe hot aggregate with chlorine gas, thereby producing vapors ofanhydrous aluminum chloride; cooling and condensing the vapors ofanhydrous aluminum chloride and so separately obtaining the same.

5. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging aluminous ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the said ore and causing it totravel longitudinally through the said kiln; applying to the said ore ata point near the charging end of the said kiln a small percentage ofliquefied aluminum chloride sludge sufficient to saturate the aluminousore therewith; maintaining the temperature in the said kiln within arange that will carbonize the applied sludge; carbonizing the appliedsmall percentage of sludge and thereby producing an aggregate ofcarbonized aluminum chloride sludge and aluminous material; successivelyapplying and carbonizing additional small percentages of aluminumchloride sludge with the said aluminous ore during its longitudinalpassage through the said kiln until the carbon content of the saidaggregate is at least 0.45 pound per pound of oxygen in the aluminouscontent thereof; discharging from the kiln an aggregate of fullycarbonized aluminum chloride sludge and aluminous ore having a poresurface of at least 100 square meters per gram of aggregate; chargingthe said aggregate to a retort at a temperature between 1000 F. and 1500F. and there reacting the hot aggregate with chlorine gas, therebyproducing vapors of anhydrous aluminum chloride; cooling and condensingthe vapors of anhydrous aluminum chloride and so separately obtainingthe same.

6. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging aluminous ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the said ore and causing it totravel longitudinally through the said kiln; applying a small percentageof liquefied aluminum chloride sludge to the aluminous ore at a pointnear the charging end of the said kiln; maintaining the temperature inthe said kiln Within a range that will carbonize the applied sludge;carbonizing the applied small percentage of sludge and thereby producingan aggregate of carbonized aluminum chloride sludge and aluminousmaterial; successively applying and carbonizing additional smallpercentages of aluminum chloride sludge with the said aluminous oreduring its longitudinal passage through the said kiln until the carboncontent of the carbonized aggregate is at least 0.45 pound per pound ofoxygen in the aluminous content thereof; discharging from the kiln anaggregate of fully carbonized aluminum chloride sludge and aluminous orehaving a pore surface area of at least 100 square meters per gram ofaggregate; charging the said aggregate to a retort at a temperaturebetween 1000 F. and 1500" F. and there reacting the hot aggregate withchlorine gas, thereby producing vapors of anhydrous aluminum chloride;cooling and condensing the vapors of anhydrous aluminum chloride and soseparately obtaining the same.

7. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging aluminum ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the said ore and causing it totravel longitudinally through the said kiln; applying a small percentageof liquefied aluminum chloride sludge to the aluminous ore at a pointnear the charging end of the said kiln; maintaining the temperature inthe said kiln within a range that will carbonize the applied sludge,while not heating the material-in-process above approximately 1600 F;carbonizing the applied small percentage of aluminum chloride sludge;successively applying and carbonizin g additional small percentages ofaluminum chloride sludge with the said aluminous ore during itslongitudinal passage through the said kiln; discharging from the kiln anaggregate of fully carbonized aluminum chloride sludge and aluminousore; charging the said aggregate to:a retort at a temperature between1000 F. and 1500 F. and there reacting the hot aggregate with chlorinegas, thereby producing vapors of anhydrous aluminum chloride; coolingand condensing the vapors of anhydrous aluminum chloride and soseparately obtaining the same.

8. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging aluminous ore to a heated horizontal rotary kiln;rotating the kiln and thereby tumbling the said ore and causing it totravel longitudinally through the said kiln; applying a small percentageof liquefied aluminum chloride sludge to the aluminous ore at a pointnear the charging end of the said kiln; maintaining the temperature inthe said kiln within a range that will carbonize the applied aluminumchloride sludge, while not heating the material-in-process aboveapproximately 1600 F.; carbonizing the applied small percentage ofsludge and thereby producing an aggregate of carbonized aluminumchloride sludge and aluminous material; successively applying andcarbonizing additional small percentages of aluminum chloride sludgewith the said aluminous material during its longitudinal passage throughthe said kiln until the carbon content of the fully carbonized aggregateis at least 0.45 pound per pound of oxygen in the aluminous contentthereof; discharging from the kiln an aggregate of fully carbonizedasphalt and bauxite; charging the said aggregate to a retort at atemperature between 1000 F. and 1500 F. and there reacting the hotaggregate with chlorine gas, thereby producing vapors of anhydrousaluminum chloride; cooling and condensing the vapors of anhydrousaluminum chloride and so separately obtaining the same.

9. The process of manufacturing anhydrous aluminum chloride whichcomprises: charging to a heated horizontal rotary kilna major portion ofaluminous ore and a minor portion of coke; rotating the kiln and therebytumbling the aluminous ore and coke and so causing them to travellongitudinally through the said kiln; applying a small percentage ofliquefied aluminum chloride sludge to the said major portion ofaluminous ore and said minor portion of coke at a point near thecharging end of said kiln; maintaining the temperature in the said kilnwithin a range that will carbonize the applied aluminum chloride sludge;carbonizing the applied small percentage of aluminum chloride sludge andthereby producing an aggregate of carbonized aluminum chloride sludgeand coke and aluminous ore; successively applying and carbonizingadditional small percentages of aluminum chloride sludge with the saidmajor portion of aluminous ore and said minor portion of coke during thelongitudinal passage of the material-in-process through the said kilnuntil the total carbon in the aggregate constitutes at least 0.45 poundper pound of oxygen in the aluminous content thereof and until thecarbonized aluminum chloride sludge at least equals in weight the saidminor portion of coke initially charged to the kiln with the aluminousore; discharging from the kiln an aggregate of fully carbonized aluminumchloride sludge and coke and aluminous ore; charging the said aggregateto a retort at a temperature between 1000 F. and 1500 F. and therereacting the hot aggregate with chlorine gas, thereby producing vaporsof anhydrous aluminum chloride; cooling and condensing the vapors ofanhydrous aluminum chloride and so separately obtaining the same.

10. The process of manufacturing anhydrous aluminum chloridewhichcomprises: charging to a heated horizontal rotary kiln a major portionof aluminous ore and a minor portion. of. coke, said coke not exceedingin weight one sixth of the weight of the aluminous ore; rotating thekiln and thereby tumbling the aluminous ore and coke and so causing themto travel longitudinally through the said kiln; applying a smallpercentage of liquefied aluminum chloride sludge to the said majorportion of aluminous ore and said minor portion of coke at a point nearthe charging end of said kiln; maintaining the temperature in the saidkiln without a range that will carbonize the applied aluminum chloridesludge; carbonizing the applied small percentage of aluminum chloridesludge and thereby producing an aggregate of carbonized aluminumchloride sludge and aluminous material; successively applying andcarbonizing additional small percentages of aluminum chloride sludgewith the said major portion of aluminous ore and said minor portion ofcoke during the longitudinal passage of the material-in-process throughthe said kiln until the total carbon in the aggregate constitutes atleast 0.45 pound per pound of oxygen in the aluminous content thereof;

References Cited in the file of this patent UNITED STATES PATENTS1,099,096 McAfee June 2, 1914 1,147,832 Kiegelgen et a1. July 27, 19152,084,290 McAfee June 15, 1937 2,357,621 Tuttle Sept. 5, 1944 UNETEDSTATES PATENT OFFICE TERTIFICATE @F EGRRECTIQN Patent No, 2,835,554 May20 1958 williamA Pardee It is hereby certified that error appears in theprinted specification of the above rluzrfizxawed patent requiringcorrection and that the; said Letters Patent should read as correctedb'a'lowu Column 2, line 35, after "just described" insert is discharged"5-21 Signed and sealed this 5th day of August 1958..

(SEAL) Attest:

KARL AXLINE ROBERT C. wmscm Attssting Officsr Qmmissiamr at Pater-252s

1. THE PROCESS OF MANUFACTURING ANHYDROUS ALUMINUM CHLORIDE WHICHCOMPRISES: CHARGING ALUMINOUS ORE TO A HEATED HORIZONTAL ROTARY KILN,ROTATING THE KILN AND THEREBY TUMBLING THE SAID ORE AND CAUSING IT TOTRAVEL LONGITUDINALLY THROUGH THE SAID KILN, APPLYING A SMALL PERCENTAGEOF LIQUEFIED ALUMINUM CHLORIDE SLUDGE TO THE ALUMINOUS ORE AT A POINTNEAR THE CHARGING END OF THE SAID KILN, MAINTAINING THE TEMPERATURE INTHE SAID KILN WITHIN A RANGE THAT WILL CARBONIZE THE APPLIED SLUDGE,CARBONIZING THE APPLIED SMALL PERCENTAGE OF SLUDGE, SUCCESSIVELYAPPLYING AND CARBONIZING ADDITIONAL SMALL PERCENTAGES OF ALUMINUMCHLORIDE SLUDGE WITH THE SAID ORE DURING ITS LONGITUDINAL PASSAGETHROUGH THE SAID KILN, DISCHARGING FROM THE KILN AN AGGREGATE OF FULLYCARBONIZED ALUMINUM CHLORIDE SLUDGE AND ALUMINOUS MATERIAL, CHARGING THESAID AGGREGATE TO A RETORT AT A TEMPERATURE BETWEEN 1000*F. AND 1500*F.AND THERE REACTING THE HOT AGGREGATE WITH CHLORINE GAS, THEREBYPRODUCING VAPORS OF ANHYDROUS ALUMINUM CHLORIDE; COOLING AND CONDENSINGTHE VAPORS OF ANHYDROUS ALUMINUM CHLORIDE AND SO SEPARATELY OBTAININGTHE SAME.